Which of the following patients should not engage in high-temperature operation?

Patients with heart disease should avoid high-temperature operation due to the strain that heat can place on cardiovascular function. High temperatures can lead to vasodilation, where blood vessels expand to release heat. For someone with heart disease, this can increase the workload on the heart, potentially leading to complications such as heart attacks or exacerbation of existing conditions.

In contrast, while asthma, high blood pressure, and diabetes can present their own challenges in high-temperature settings, the immediate risks associated with elevated heart rates, dehydration, and circulatory issues make heart disease the most critical condition to consider for avoiding high-temperature environments. Individuals with asthma might struggle with heat and humidity affecting their breathing, and those with high blood pressure could experience issues in hot conditions, but the cardiovascular load from heat is particularly dangerous for someone with pre-existing heart conditions. Thus, individuals with heart disease are advised to steer clear of high-temperature operations to safeguard their health.