It has been four days since Savannah Guthrie's mother Nancy was abducted from her home in the middle of the night. 

Police have said they still hope to find the 84-year-old alive, but fears are growing that time may be running out because of her underlying health issues. Nancy, who lived alone in the affluent Catalina Foothills in Arizona, was last seen at around 9.45pm on Saturday.

When she failed to show up at church on Sunday, her family reported her missing after finding droplets of blood dotting the foyer of her $1 million property.

And now, her medical vulnerabilities are coming into sharper focus. Authorities have not revealed the full extent of her health problems, but police have said that she is frail and has mobility issues that limit her ability to walk long distances.

In an audio dispatch recording published last night, the Pima County Sheriff's Office said Nancy has high blood pressure and cardiac issues.

She requires daily medication. Sheriff Chris Nanos said Tuesday: 'If she's alive right now, her meds are vital. I can't stress that enough.' 

It is also known that she has a pacemaker synced to her Apple devices – and that it later disconnected, possibly because it went out of range. 

Now, doctors told the Daily Mail the limited details released so far paint a worrying picture – and warned that without rapid intervention, her condition could deteriorate rapidly.

While there is no indication that her pacemaker has been deactivated, the fact that she has one gives insight into her health.

It suggests Nancy has a significant underlying heart rhythm condition that has required medical intervention. 

A pacemaker malfunction can be life-threatening, potentially leading to collapse, loss of consciousness or fatal cardiac arrest. 

Even with a functioning pacemaker, being without her essential medications poses a severe and escalating threat. 

Combined with her mobility issues and known medical needs, doctors warn she is now in critical condition. Without immediate care, her life could be in danger within days.

Dr Elizabeth Klodas, a board-certified cardiologist based in Minnesota who has not seen Nancy as a patient, told Daily Mail: 'The fact that Ms Guthrie has a pacemaker indicates she has heart disease.

'However, a pacemaker, in and of itself, would not restrict her from leaving her house on her own.' 

More likely, said Klodas, was that she also suffers cardiovascular disease caused by plaque building up inside the arteries – known as atherosclerosis – which can raise the risk of a heart attack or stroke.

This buildup can affect different parts of the body. In the heart's arteries, it can trigger chest pain (angina) and heart attacks. 

In the arteries leading to the brain, it can increase the risk of stroke. And in the legs, it can restrict blood flow and cause pain while walking or mobility problems.

Coupled with other common issues such as high blood pressure and diabetes, these problems can quickly mount. Klodas adds: 'Not taking the medications needed to control these risk factors could prove fatal in 24 hours.' 

Pacemakers are relatively common, particularly in over-65s – around three million Americans have one. Newer devices can transmit data wirelessly.

Patients are typically given a small bedside monitor that communicates with the pacemaker overnight, collecting information such as battery levels and heart rhythm logs.

It then sends this data via Wi-Fi or a cellular connection to a secure system that doctors can access remotely.

When it comes to the vital medication Nancy could be on, Dr Carole Lieberman, a psychiatrist based in California who has also not treated Guthrie, told the Daily Mail: 'The most likely medication that she's taking would be anticoagulants or antiarrhythmic medication. 

'She might also be taking medication for heart failure.'

If she went on to suffer a stroke as a result of lacking her daily medication, it could be severe or even fatal - especially if treatment is delayed beyond 30 minutes.

The event could disrupt the brain's ability to control movement, potentially causing paralysis or profound weakness on one side of the body.

Simultaneously, it could cloud the person's mind, affecting speech, memory and the capacity to make decisions or understand a situation, rendering them unable to call for help or assist in their own rescue.

In a photo taken with her daughter, Nancy appeared to have extensive bruising on her hand and forearm. 

Dr Ankur Kalra, a cardiologist at SUNY Upstate Medical University, told Daily Mail that this suggests Guthrie takes anticoagulants. 

Commonly known as blood thinners, anticoagulants reduce the blood's ability to clot -helping prevent dangerous clots that can trigger strokes and other life-threatening events. 

Klodas, also the co-founder of Step One Foods, said: 'Losing access to blood pressure-lowering medications - especially if multiple drugs are required to keep blood pressure in check - can be catastrophic.'

As the investigation continues, Savannah took to social media to ask people to 'please pray' for her mother. 

She wrote: 'We believe in prayer. we believe in voices raised in unison, in love, in hope. we believe in goodness. we believe in humanity. above all, we believe in Him.'